Maryland and Delaware have absolutely no tax, I always wonder why people neighboring those states don't just drive an extra 40 miles to buy their cars so they don't get taxed a couple grand. I've always wondered If the government knows that people do that.
People do, but most are technically still on the hook for the sales tax. For example, I live in Massachusetts; New Hampshire, which has no sales tax, is just a short trip to the North. However, Massachusetts has a "use tax" which essentially states that you have to pay sales tax on anything purchased and brought into Massachusetts if you haven't already paid that sales tax in the state where it was purchased.
Also, if I were to buy an item in another state having either a lower or higher sales tax than Massachusetts then I'd either have to pay the difference in tax or I'd be eligible for a refund of my overpaid sales tax.
Massachusetts seems to know that not many people are going to keep track of all their out of state purchases (to include internet orders) so they offer something called a safe harbor tax which will cover your out of state purchases. This safe harbor tax is based on a percentage of your earnings and is usually less than you would pay if you itemized all your purchases. This safe harbor tax doesn't apply to big ticket items (>$1000 ?); you still have to itemize those out of state purchases.
Funny thing is not many people I talk to even seem to know they are supposed to be paying this tax. A colleague even told me that her paid tax preparer asked her "Did you make any out of state purchases this year?" all the while shaking his head side to side to encourage her to answer "no" so he could file her taxes as such and get her a bigger return.
We do have a tax free weekend coming in August so I'll likely wait until then to replace my 2007 iMac.